Put everything except the butter in a large pan or in a slow cooker. Allow it to come to boil and then simmer until soft ( roughly 30 mins).
If using slow cooker put on medium for 4-6 hours or longer.
Then blend and add the butter (or coconut cream if want it dairy free) until smooth. Add more water if its too thick for your liking.
Serve with chopped raw carrot 'croutons'.
Notes
To save time when using a slow cooker don't bother to chop any of the veg, just half the potatoes and place in pot with water. Feel free to add spice, more coconut or other veg to this soup!